Formation tester for drilling with casing



J. E. ORTLOFF Filed Nov. 29, 1954 FORMATION TESTER FR DRILLING WITH CASING Feb. 4, 1958 United States Patent FORMATION TESTER FOR DRILLING WITH CASING John E. Ortlof't, Tulsa, Okla., assignor to Esso Research and Engineering Company, a corporation of Delaware Application November 29, 1954, Serial No. 471,710

3 Claims. (Cl. 166-115) has been placed in the well bore. Apparatus is provided which may be suspended on a wire line to be lowered downwardly through the casing of a well. The tester of this invention is supported from the lower termination of the casing so as to extend beneath the casing. Fluid ports are provided to permit access of well tluids into a sample chamber of the arrangement. The formation tester may then be recovered by use of a wire line and the trapped fluid sample can be recovered for examination at the surface of the earth.

At the present time, a great deal of work is being carried out to develop an attractive technique for drilling with casing." In this technique, the objective is to employ large diameter casing rather than smaller diameter drill pipe in the operation of all drilling steps. In drilling with casing, a retractable drill bit is employed of such a nature that the bit can be lowered through the casing on a wire line to be latched in drilling position at the bottom of the casing. Expansible cutting edges of the drill extend outwardly when the drill is latched in position so as to drill a borehole somewhat greater in diameter than the casing. In this arrangement, the drill bit can be retrieved by a wire line to be pulled upwardly through the casing when it is necessary to service or replace the drill bit. Consequently, as drilling proceeds, additional lengths of casing are added without any necessity for removing the casing from the borehole. l

To secure the full benelits of drilling with casing, it becomes attractive to develop means for conducting all normal borehole operations, as well as drilling, without necessity for removing the casing from the borehole. For example, in normal drilling operations, so-called formation testers are frequently employed during drilling to de-v termine whether or not there is any production of oil or other uids at diiferent levels in a borehole. Conventional formation testers are adapted for use on a drill string and are not adaptable for testing formations without removing the entire drill string from the borehole. It is therefore the principal objective of this invention to provide a formation tester which can be operated to sample well fluids without necessity for removing the well casing.

The advantageous features'and nature of this invention can be fully understood by reference to the attached drawings. The drawings illustrate a preferred embodiment of the invention in cross-sectional elevational detail.

lFigure l illustrates the entire formation testing arrangement in operative position in a casing at the bottom of a borehole;

Figure 2 illustrates a shear pin arrangement which is preferably employed in the apparatus of Figure l during lowering of the formation tester into the casing; and

lFigure 3 illustrates the sample chamber of the formation tester and the Spearhead provided for the wire line operation of the apparatus, and constitutes an upper continuation of the apparatus shown in Figure 1.

For the purposes of this invention, it is assumed that drill hole 2 is cut into the earth by a drilling with casing technique. Thus, a retractable drill bit having extensible cutting teeth, is operated from the casing extension sub 3 so as to drill the borehole 2. When drilling has proceeded to a depth at which it is desired to conduct a formation test, the retractable drill bit is recovered from the casing sub 3 by means of a wire line. A drill bit is then lowered into the casing to drill a small diameter pilot hole 4 beneath the larger diameter borehole 2. A conventional retractable drill bit may be used to drill the pilot hole providing that the cutting teeth of the drill bit are held in a non-expanding position so as to drill a borehole substantially equal to the inner diameter of the casing 1. This drill bit is then removed from the casing by means of a wire line and the tool of this invention may then be employed to conduct a formation test in the pilot hole 4. Further details of the techniques used for drilling the borehole 2 and the pilot hole 4 by a drilling with casing technique are not considered necessary for an understanding of this invention. As indicated, drilling of the borehole 2 andthe pilot hole 4 may be carried out by known and conventional techniques.

The apparatus of this invention includes all of the mechanical elements illustrated in the drawing within the casing 1 of which sub 3 is an extension. Thus, the apparatus generally includes a Spearhead 5 as the uppermost section surmounting a cylindrical chamber 6 which is provided to contain fluids obtained during.

formation testing. The central portion of the formation tester includes upper and lower latches 7 and 8 for locking the formation tester in the casing. The' lowermost portion of the formation tester is provided with a packer arrangement 9 for sealing the formation tester in the pilot hole 4. Fluids which may be present in the strata communicating with the pilot hole 4 may obtain access to the sample chamber 6 through ports 10 owing upwardly in the interior of the apparatus past the poduction valve 11 into the sample chamber 6."

With this general identification of the elements of thef formation tester, the specific nature of these elements and their particular design can be appreciated. I

In order to provide a suitable latching arrangement forv the formation tester, a central cylindrical portion of` the tester identified by numeral 12 is machined to have an upper termination of reduced diameter indicated by` numeral 13. Reduced section 13 is fabricated to have a smaller outside diameter than the remainder of cylinder 12. The lower termination of outer cylindrical element 17, to which the upper cap portion 21 of the sample chamber 6 is threadably attached, is similarly machined to have an inner bore 14 adapted to t over reduced section 13 of cylinder 12 in a reciprocal sliding relationship. Sealing means 23 is provided to maintain a uid tight condition between element 17 and reduced section 13 as illustrated. Cylindrical element 17 and portions 12 and 13 in assembled condition are adaptedV to be lowered and moved vertically within the casing extension sub 3 as shown.

Upper latching dogs 7, two of which are illustrated,"

are pivoted by means of pins 47 in recesses 15 of cylindrical element 12.. Slots 25 are provided in the' outer cylindrical element 17 so as to v'generally register with'.v

bottom edge or end of cylindrical element 17y by what:`x

Patented Feb. 4, 1958 upwardly wit-h'respect to element-v 121s0-that the lip 16' 5 ofthe'slotfinselement 17'will belforced-upwardly against the`tooth'50 provided on latchf'. This w-i-ll fha-ve the .re-y sultofforcing the latch 7 intoaretractedlposition'withinv its..slot 15.. However, when the weight ofthe-formation tester vistalien off the wire lineas Willbe described, ele- 10 ment *.17 can slide-downwardlywith respectlto elementlZ, permitting the latch 7 to extendoutwardly toithepositionr illustrated.

Lower latching elements s-whicharepivotedon pins tirrrecesses 26. of cylindricalelement l2.are.:also.pro 15 vided'.` Both latches 7 and .8.lare-biased-outtvardly. by means-1 of bowed springs 18.`

The manner in which these` elements Voper-.atacan:now be; fully f appreciated. When the.' formation f tester of. this invention is. to be employed, the casing extension.' sub 20 rwill belifted somewhat aboveitheiioor of fthe: borehole 2. A: wire line will thenbeattached to: Spearhead' 5 fof. the formation tester, and-the tester. will be. loweredzdown.- wardly through thecasing.'V As.V described abovegduring.

thelowerin'g operation, the upper: latches 7vvill1 be held 25 in a. retracted position. Consequently, the; formation. tester may. be: dropped. downwardly.` throughE s .thercasing until the' lower latches 8'contactthenshoulderrof the: lower groove 19, machined in the lower portionfof casing.

3. Springs 18l forcinglatches` 8ioutwandlyrintosgro'ove 30 19fwill resultw in. locking theformation; tester: against further downward movement.' Consequently, theiweight ofthe formationA tester will be transferred .fromthespeaxhead 5 to the latches 8. This will permit cylindrical element 17 to slide downwardly with respectA to cylindrical 35 element 12 permitting upper latching dogs 7 to` extend outwardly into the upper groove 20 provided inzcasing. sub 3. It desired, thel wire line canthenfbezremoved. from Spearhead 5. When the'casing 1 and thecasing sub 3 are then lowered in the. borehole, the'extending 40 termination of the-formation tester will be brought into contact. with the bottom of pilot hole4. A` portionzof the weightof the casing land casing extension sub 3 can then be forced downwardly on the. formation tester through the. upper latchng. dogs 7. latches 7 and-8 cooperateito locky the formation tester with respect to. both upwardand downward-.movement relative to the casing.

The lower termination: of cylindrical .member 1-2. is` attached to nestoveran upper. termination of the lowermost cylindrical element 24.` Cylindrical.,members 12 and 24 are therefore -arrangedfor telescopic slidingmove meut. A .packer` 9 is circumferentially arranged? about thejoint betweennesting elements-12 and24. Thmuppermost portion ofipacker.' 9 isf sealed =in element 12fwlrile. thelowerrnost portion of packer9 is .sealed in elementi24 Consequently, when. the lower 'portion' of the. formation tester is forced against thebottornof the pilothole.v 4, cylindrical element 24`Iwill be. forced upwardly with respect to cylindrical-element 12, causing packer 9-toibe 60 forced outwardly againstrthe walll of pilothole-.14. rEhe lower portion of the. formation tester willethen be sealed. in pilot hole 4.so1as to exclude drillingj mud existent:in borehole 2.

Fluid which may flow from strata adjacent pilot'. hole G5 rodflikeyalve member xedl to KAor integral withthe lower 75 I" In thismanner, 4"

terminationofcylindrical. member. 24. Valve 27 will.

be seated against valve seat 28 so as to prevent fluid flow past the valve as long as cylindrical element 24 is at its lower limit of movement with respect to cylindrical element 12. Thus, while the formation tester is being lowered through the casing,.the.weight of the elements of the apparatus will tend to cause valve 27 to maintain its closed position... On. the. other hand, the resistance. of drilling mud in the boreholewilltend to force cylindrical element 24 upwardly asthe tool is lowered, which would tend to open valve. 27.' To prevent the possibility of valve 27 opening, before the formation tester is in sampling position, a` shearpi-n 305 maybe passed through valve 27, locking it in cylindrical element 12 as shown in Figure 2. Shear pin 30y is adapted to break when the casing is lowered so as to force the bottom of the formation tester against the bottom of pilot hole 4. Breakage of the shear pin will permit valve 27 to open at' thesame time that packer 9 isI forced against. the wall. of. the: borehole 4. Fluid may-then ow through .ports lthupwardly pastvalve 27 and intosample chamber' 6'.y

Whenasample'of the well fluids has .been'obtained in this manner, theformation tester can be retrieved through the-casingby aixingcaawire :linetosp'earhead 5. In the retrieving operation; the dcasingzl. and casing 'sub .3' will be liftedfsomewhat offthe: bottom .offthe-.borehole caus ing cylindrical.element.121.toslideupwardly with respect to cylindrical element 24z1permittingjpacker.25:to collapse. This willfalso. tend to; cause; valve-27"'to'.:seat, so as to seal..the.'sample:V Huid; in samplefchamber 6. To secure positivey closure iofvalve 27 a. springl 33 may be positioned about the valve stem bearingtagainst lip :3.4ofcylindrical element .12.. Spring 331 willthus positively force closure of valve'27-when casing sub: 3 :isrlifted zintheborehole.

The formation tester' can' be; retracted through.` the casing automatically when'. the wire. linen attached.. to4

in the sample chamber 6? to ypermit the trapped lluids to be bled out of the sample chamber.

As described, the essentialand. operative'y elements of the formation tester of this invention include -the following features; First, retractableV latching .means are provided to positively' lock the formation tester-in the lower termination of a casing. These latching'means are so positioned that when the formation testerris locked at the lowerterminationof the casing, aportion, of the formation ltester extendsbelowrthe casing into a small diameter pilot hole. Packing. means are provided about the lower portion of the tester'so asto .seal the Vformation tester in the pilot hole 4'.- Ports.cut1throughthe yformation tester below the packer provide access foruids permitting lluids to flowupwardly into an interior sample' chamber of the formation tester. A-valve1is employed to prevent ow of uid into the sample; chamber until the packer has been operatedto seal the formation tester in the pilot borehole.

In the preferred -embodiment of this invention in which the specific elements described are employed to provide v the essential functionszidentied, a number ofadvantageous features are; appreciated; For one thing, the

0 formation tester is adapted to positively lock in the lower termination of the casingwhile' atthe Sametime, means are provided to. permit the positive Withdrawal of the formation tester from the casing. The. valve arrangement describedprovides fool proof means tofeliminate entrance of drilling mud into the sample chamber ofn the apparatus, while the tool is being lowered to formation testing position. Again this valve causes sampled iluid to be trapped in the sample chamber at the pressure existent in the borehole whensampled. An additional feature of the apparatus described is the simplicity of the packing arrangement which may be used to seal the formation tester in the borehole during a formation test.

The patentable novelty of the invention described is defined by the following claims.

What is claimed is:

1. A formation tester adapted to be used when drilling with casing which comprises in combination an elongated cylindrical casing extension sub secured to the lower end of the casing within a bore hole, an elongated cylindrical body portion, an outer cylindrical element surrounding an upper portion of the cylindrical body portion in a vertical sliding relationship, means for lowering said outer element, said cylindrical body portion and said lower element in an assembly form within said sub, retractable upper latching means and lower latching means pivotally mounted on said cylindrical body portion and arranged to engage upper and lower recesses within said casing sub, said upper latching means engaging said upper recesses through ports in said outer cylindrical element when said outer cylindrical element moves downward relative to said elongated cylindrical body portion, said lower latching means being arranged to engage said lower recesses when said lower cylinder element moves vertically upward relative to said cylindrical body portion, a sample chamber disposed within said assembly, packing means ixed to said elongated body portion and said lower cylindrical element and arranged to be expanded against the wall of lthe bore hole in response to vertical upward movement of said lower cylindrical element relative to said body portion, at least one port providing lluid access from the bore hole at a point below said packing means to a point Within said sample chamber and valve means intermediate said port and said sample chamber actuatable to seal lluid within the sample chamber.

2. An apparatus as defined in claim 1 in which the valve means is a spring loaded normally closed valve arranged to open when the lower cylindrical element moves vertically upward relative to the cylindrical body portion a distance sufficient to expand the packing means.

3. A formation tester for use beneath a casing suspended in a bore hole comprising in combination a cylindrical extension sub secured to the lower end of the casing, an elongated cylindrical body portion having a central chamber adapted to move vertically within and to extend partially below said sub, said body portion including two cylindrical elements maintained in nesting sliding relationship including ports in the outermost of said elements, the inner element being provided with pivotally mounted latching dogs retractably arranged to move through the ports in the outer element and to engage with recesses in the inner surface of the casing extension sub, packing means mounted on said cylindrical body portion and arranged to seal the annular space between the body portion and the wall of the bore hole below the sub, lluid ports arranged in the body portion below said packing means and arranged to provide fluid access from the bore hole into the central chamber, and valve means arranged to seal bore hole lluid within the interior chamber.

References Cited in the le of this patent UNITED STATES PATENTS 1,142,460 Roby June 8, 1915 1,295,969 Carmichael Mar. 4, 1919 2,094,022 Pennington Sept. 28, 1937 2,113,856 Parks Apr. 12, 1938 2,239,996 Chappell Apr. 29, 1941 

